1. Field of the Technology
The present invention relates to a technology of localized mobility management (LMM) network, and more particularly to a method, system, and device of packet routing for an LMM network.
2. Background
A network-based localized mobility management (NETLMM) system is capable of supporting the movement of a mobile terminal within a certain area (belonging to the same local management domain) without changing the IP address before and after the movement. The mobility function is achieved through a network, and has no special requirements on the terminal. These advantages may promote the application of the NETLMM system.
In response to this requirement, the IETF has established a special working group called NETLMM, for research, and proposed a NETLMM basic protocol solution and protocol flow. FIG. 1 is a structural view of a NETLMM framework with a single local mobility anchor point (LMA or LMAP).
The localized mobility management (LMM) follows the framework shown in FIG. 1. The LMA stores and maintains routing information to each mobile node (MN), and each piece of routing information is directed to a media access gateway (MAG) that the MN is currently accessing. Packets sent to or from the MN are forwarded by the LMA. When an MN moves from one MAG to a new MAG, the new MAG sends a message to the LMA to update the routing information corresponding to the MN on the LMA. The movement of MN is detected through a mobility detection mechanism by network equipment, so the MN does not need to have a special mobile protocol capability. Before and after the movement, the IP of the MN remains unchanged, and the undergoing session will not be interrupted, thereby achieving the mobile capability. In this framework, the MAGs may be replaced by access routers (ARs).
An LMM protocol implemented by network devices is also proposed by the IETF based on the above framework. FIG. 2 shows a data forwarding path between an MN and a corresponding node (CN) thereof according to this protocol. As seen from this protocol, data sent from the MN must pass through an MAG and an LMA, and then routed to the destination after arriving at the LMA. As such, even if the CN and the MN are under different MAGs in the same NETLMM domain, data packets must be forwarded by the LMA. That is, the data packets are transmitted in a path of: MN→MAG1-tunnel→LMA-tunnel→MAG2→CN. As a result, alternative routing occurs, which may increase the transmission delay and reduce the system efficiency.